Noun
merde (uncountable)
(humorous, nonstandard) Shit.
The story of the refusal of the guard to surrender is false as historically not only did the guard surrender, but Pierre Cambronne, the man portrayed as saying "merde", denied ever having said this. Source: Internet
XVII; in French the words mère de (meaning "mother of") sound like merde, which means "shit". Source: Internet